section views. used to describe interior details of a part that cannot be seen in an orthographic...
TRANSCRIPT
CHAPTER 12Section Views
Section Views
Used to describe interior details of a part that cannot be seen in an orthographic view Eliminates the need to dimension hidden
lines Better describes the shape than hidden
lines Easier to understand
Cutting plane lines Shows the location of the section
view (where the part has been cut) Can be multiple line types
Simplified cutting plane
Arrowheads
Indicate the direction of sight Points toward the area to be
described in the section view Most common mistake is to point arrows
the wrong direction
Crosshatching (Section lines)
Used to show the material that has been cut by the cutting plane line
Guidelines for crosshatching Typically drawn at 45˚ 30˚ and 60˚ also common Any angle between 15˚ and 75˚ is acceptable
Cannot be parallel or perpendicular to any object lines
Must be evenly spaced Spacing must ensure that it’s understood to be
crosshatching
Common hatching mistakes
Crosshatching styles(coded section lines)
Can be used to represent specific materials Not commonly used on engineering drawings
Section views of thin parts If part is too thin to see hatching thin
parts are commonly filled
Types of section viewsFull Sections
Cutting plane line extends completely through the part
Usually through the center of the part or a feature on the part
Half Sections
The section view is half sectioned and half orthographic view Used on symmetrical parts
Offset Sections
Cutting plane line is staggered to pass through multiple features that are not on the same plane View is drawn as if all features are on the
same plane
Aligned Sections
Cutting plane line is staggered to pass through offset features
Section views drawn as if the cutting plane is rotated to the plane perpendicular to the line of sight
Unsectioned Features
Some features that appear on the cutting plane are left without crosshatching
Bolts Nuts Rivets Screws Springs Shafts Bearings
Gear teeth Pins Keys Ribs Webs Spokes
Can be difficult on 3D CAD
Conventional Revolutions
For symmetrical objects Practice of revolving features to the cutting
plane of the section view of a symmetrical part
All symmetrical features revolved to the cutting plane
Showing these features in true projection would result in confusion
Difficult to do with CAD Drawing data is tied to 3D models, so it can
be hard to follow this practice
Broken-out Sections
Small area of a standard orthographic view is removed to show details behind it
No cutting plane line Hard to tell the location of the section
Auxiliary Sections Section view that appears as an auxiliary
view
Using Section Views in place of orthographic views Acceptable to replace orthographic views with section views
Must make sure that no details of the part are omitted by removing an orthographic view
Conventional Breaks
Used to show a part that is a constant shape for a long length Makes the view shorter/take up less
space 2 methods of showing breaks
Revolved Sections
Section view is revolved 90˚ about a centerline on an orthographic view Superimposed on view Can be broken away or not
Removed Sections
Similar to revolved except they are removed from the orthographic view
Labeling section views Necessary when there is more than one
section view on a drawing or the scale of the section view differs from that of the drawing
Views are labeled alphabetically Letters are placed at the ends of the
cutting plane line or arrows Large text: .2-.25 tall
View labels Labels placed under section views
SECTION A-A (large text) Letters not used: I, O, Q, S, Z (look like
numbers)
Arrangement of drawing views Section views should be arranged in
order that they are labeled (alphabetically)
Makes them easier to find